Novel photographic elements and means for rapid processing of photographic elements

ABSTRACT

A photographic element comprising an acrylic interpolymer can be rapidly processed at high temperatures to provide an image record exhibiting reduced haze and improved photographic properties. The acrylic interpolymer contained in the photographic element is compatible with gelatin and has a Tg of less than 20* C. In another aspect of this invention, a photographic element comprising an acrylic interpolymer and a development modifier exhibit improved photographic properties.

United States Patent Taber et al.

[ Mar. 7, 1972 [54] NOVEL PHOTOGRAPHIC ELEMENTS AND MEANS FOR RAPIDPROCESSING OF PHOTOGRAPHIC ELEMENTS [72] Inventors: Robert C. Taber;William H. Russell, both of Rochester, NY.

[73] Assignee: Eastman Kodak Company, Rochester,

[22] Filed: Feb. 1, 1968 [21] Appl. No.: 702,381

Related US. Application Data [63] Continuation-in-part of Ser. No.649,697, June 28,

1967, abandoned.

[52] U.S.Cl ..96/66.5, 96/125 [51] Int. Cl. ..G03c 1/08,G03c 5/30 [58]Field of Search ..96/66, 66.3, 95, 125

[56] References Cited UNITED STATES PATENTS 3,179,517 4/1965 Tregilluset al. ..96/29 3,295,976 1/1967 Abbott et a1 ..96/55 3,458,317 7/ 1969Ditzer et al. ..96/94 3,459,790 8/1969 Smith et al ..260/483 OTHERPUBLICATIONS L. Larmore, Introduction to Photographic Principles,Prentice Hall, lnc., Englewood Cliffs, N.J., 1950, pps. 112, 117, 118,119.

Primary Examiner-Norman G. Torchin Assistant Examiner-Alfonso T. SuroPico Attorney-William H. .l. Kline, Bernard D. Wiese and Gerald E.Battist [57] ABSTRACT A photographic element comprising an acrylicinterpolymer can be rapidly processed at high temperatures to provide animage record exhibiting reduced haze and improved photographicproperties, The acrylic interpolymer contained in the photographicelement is compatible with gelatin and has a Tg of less than 20 C. Inanother aspect of this invention, a photographic element comprising anacrylic interpolymer and a development modifier exhibit improvedphotographic properties.

25 Claims, 1 Drawing Figure U U Q G U O Q Q a DE VE L 0P F/X PATENTEDMAR7 I972 er on bar/1 sides) F W EXPOSED SHEET FILM (emulsion lay WASHDEVELOP A TTOR/VEY NOVEL PHOTOGRAPHIC ELEMENTS AND MEANS FOR RAPIDPROCESSING OF PHOTOGRAPHIC ELEMENTS This application is acontinuation-in-part of U.S. Ser. No. 649,697 filed June 28, 1967, nowabandoned.

This invention relates to photographic compositions, elements andprocesses. In one aspect, this invention relates to a means forminimizing haze in photographic elements subjected to rapid processingtechniques. In another aspect, this invention relates to a method forrapidly processing a photographic element comprising a gelatino, silverhalide emulsion layer which contains an acrylic interpolymer which iscompatible with gelatin and has a glass transition temperature of lessthan about C. In still another aspect, this invention relates to aphotographic silver halide emulsion containing an acrylic interpolymerand a development modifier.

Rapid processing techniques have recently been disclosed in the priorart for quickly developing photographic elements. However, the hightemperatures and physical conditions generally encountered in rapidprocessing apparatus have resulted in a deterioration of photographicproperties of the processed element. This deterioration of photographicproperties is very apparent where emulsion layers having low gelatincontent are used to allow faster processing times and is particularlyevident in the processing of films having low gelatin content silverhalide emulsions coated on both sides of a support. The high fog andhaze resulting from the rapid processing (i.e., developing, fixing,washing, and drying) are especially objectionable.

In the prior art, attempts have been made to improve the photographicproperties of high speed emulsions by use of synthetic polymericmaterials, such as poly-N-vinyllactams, in the emulsion. However,emulsions containing poly-N-vinyllactams have often resulted in anobjectionable increase in fog and haze. Gelatin over-layers have beenproposed, as in Meerkamper, U.S. Pat. No. 3,058,826 issued Oct. 16,1962, as one solution to reduce haze problems. However, photographicelements having gelatin layers, either as the silver halide emulsionvehicles or as overlayers as disclosed in Meerkamper, exhibit relativelyhigh haze when subjected to a high temperature, unidirectional, rapidprocessing operation.

Therefore, it is an object of this invention to provide an improvedmethod for rapidly processing photographic elements.

It is another object of this invention to provide novel photographicelements which can be subjected to rapid development process.

It is another object of this invention to provide a means for producingan image record in a photographic element with a resultant low hazelevel.

It is another object of this invention to provide a novel emulsion whichcan be processed in a rapid development process to give low-backgroundfog.

It is another object of this invention to provide a novel process forrapidly developing a photographic element without substantialdeterioration of the photographic properties of an element as comparedto a conventional element processed in a similar manner.

These and other objects are accomplished in accordance with thisinvention wherein it has been found that many properties, includingresistance to abrasion, haze, fog levels, con trast, D and the like ofphotographic elements processed by rapid processing techniques can beimproved provided the processing conditions and compositions of thephotographic elements are combined as disclosed herein. In one aspect ofthis invention a photographic element having an emulsion layercontaining an acrylic interpolymer which is compatible with gelatin andhas a Tg (glass transition temperature) of less than 20 C. can beprocessed at high temperatures to achieve rapid reaction with theprocessing solutions, rapid drying and a resulting low requiredprocessing time. The photographic properties of the elements processedaccording to this invention have improved image records whereas priorart elements had to be processed at low temperatures for comparativelylong periods of time to achieve optimum image record quality.

In a typical embodiment a photographic element containing aninterpolymer such as a copoly (butyl acrylate-sodium acryloyloxy propanesulfonate) can be processed in less than two minutes at temperatures ofabove F. and preferably at a temperature in the range of about l00l20 F.to produce an element with a lower haze or opalescence than acomparative element containing gelatin as the sole binding vehicle. Theuse of acrylic interpolymers in this process actually decreases the hazelevel and provides increased resistance to abrasion as compared with anemulsion having gelatin as the sole binder vehicle. In anotherembodiment of this invention we have found that photographic elementscontaining said acrylic interpolymer in combination with a developmentmodifier can be subjected to rapid processing to produce an element withimproved photographic properties. Typical development modifiers whichcan be used in the system include nitrobenzodiazoles in which nitrogenis the sole hetero atom, S-mercaptotetrazoles, andanthraquinone-Z-sulfonic acids and their alkali metal salts. Theemulsions containing the acrylic interpolymers in combination with thedevelopment modifiers exhibit remarkable improvements in photographicproperties, e.g., they generally have lower haze, lower fog levels,increased contrast, higher D and good resistance to abrasion.

The process conditions and emulsion combinations of this invention areespecially useful in rapid unidirectional processing machines. Theaccompanying drawing shows schematically one type of a typicalunidirectional processing machine. This machine is a roller transportsystem representative of rapid processing machines which are especiallyuseful for processing X-ray films. The machine is described asunidirectional because the photographic element travels in only onedirectional path as opposed to a process wherein an element is immersedin a processing tank in one direction and is removed by movement in thereverse direction (i.e., such as by the conventional processes ofdipping a single sheet of film into a bath and pulling it out in thereverse direction). A typical apparatus for rapid processing sheet filmin a unidirectional manneris disclosed in Russell et al., US, Pat. No.3,025,799, issued Mar. 20, 1962. Typical elements processed according tothe practice of this invention comprise a film support,, such aspolyethylene terephthalate, having on at least one side of said supporta silver halide emulsion layer.

The polymers which can be used-according to this invention are acrylicinterpolymers, i.e., those interpolymers prepared from polymerizableacrylic monomers containing the characteristic acrylic group Suchpolymers are conveniently prepared by the interpolymerization of anacrylic monomer with at least one dissimilar monomer which can beanother acrylic monomer or some other different polymerizableethylenically unsaturated monomer. it is, of course, understood that theacrylic interpolymers employed in the practice of this invention arecompatible with gelatin and have Tg of less than 20 C. (Tg can becalculated by differential thermal analysis as disclosed in Techniquesand Methods of Polymer Evaluation", Vol. 1, Marcel Dekker Inc., N. Y.,1966). A similar increase in physical and photographic properties is notachieved when polymers having a Tg of above about 20 C. are employed inthe emulsions.

in one embodiment, preferred interpolymers which can be used in thisinvention comprise units of an alkyl acrylate such as, for example,methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylates (e.g.,n-butyl or t-butyl acrylates), amyl acrylates, hexyl acrylates and thelike. Acrylic interpolymers containing units of acrylic acid or asulfoester acrylate are especially useful in the process. Typicalpolymers of this type are copoly (butyl acrylate-acrylic acid), copoly(methyl acrylate-acrylic acid), copoly (ethyl acrylate-acrylic acid),copoly (butyl acrylate-sulfopropyl acrylate) and the like. In apreferred embodiment the copolymer comprises up to about 30 percent, byweight, of acrylic acid or the sulfoester acrylate; especially goodresults being obtained with latex alkyl acrylate copolymers having up toabout 20 percent, by weight, of the acrylic acid or the sulfoesteracrylate. High ratios of solubilizing groups, such as the acrylic acidgroups or the sulfoester groups produce a more soluble solution typepolymer with respect to water-carrier solvents. Mlxtures of the moresoluble-solution-type polymers and the latex polymers can be used withinthe scope of this invention to achieve the desired emulsioncharacteristics. The acrylic interpolymer generally comprises at leastpercent and to about 99 percent, by weight, of the binder vehicle forthe emulsion. In the preferred embodiments the binder vehicle comprisesfrom about 25 to about 75 percent of the acrylic interpolymer and fromabout 75 percent to about 25 percent, by weight, gelatin of the totalbinder. Generally the emulsion comprises less than 100 grams of gelatinper mole of silver halide in the emulsion to permit fast drying times ofthe developed emulsion. Preferably the emulsion comprises less than 75grams of gelatin per mole of silver halide.

In another preferred embodiment of this invention, the above-mentionedcopolymers contain units of a third monomer. Exceptionally good resultsare obtained in the process of this invention when the syntheticpolymers comprise units of 1) alkyl acrylates, (2) acrylic acid orsulfoester acrylates, and (3) an acrylic monomer unit having activemethylene groups in side chains such as in malonic ester groups,acetoacetic ester groups, cyanoacetic ester groups, or I, 3-diketonegroups such as disclosed in Smith, U.S. Pat. No. 625,593 filed Mar. 24,1967, now U.S. Pat. No. 3,488,708, issued Jan. 6, I970. Typical polymersof this class include copoly (ethyl acrylate-acrylicacid-2-acetoacetoxy-ethyl acetoacetoxy-ethyl methacrylate), copoly(butyl acrylatesodium acrylolyloxypropane sulfonate-2-acetoacetoxyethylmethacrylate), copoly (methyl acrylate-sodium acryloyloxypropanesulfonate-2-acetoacetoxylethyl methacrylate), copoly (butylacrylate-acrylic acid-Z-cyanoacetoxylethyl methacrylate) and the likeand mixtures thereof. The copolymers of (1) alkyl acrylates and (2)acrylic acid or the sulfoester can also contain units of (3)sulfobetaines, N- methacryloyl-N'-glycylhydrazine hydrachlorides, 2-[2-methacryl-oyloxy-ethyl] isothiouronium methane sulfonate and the like.Typical copolymers having sulfobetaine units include copoly (butylacrylate-acrylic acid-4,4,9-trimethyl-8-oxo-7-oxa-4-azonia-9-decene-l-sulfonate and the like.

The emulsions used in this invention may contain, for example, silverbromide, silver bromoiodide, silver chlorobromide or silverchlorobromoiodide. In particular, the processes of this invention findparticular use in developing silver halide emulsions in which the halideis predominantly bromide, i.e., at least 50 mole percent bromide. In apreferred embodiment of the invention, the emulsions contain silverhalides in which the halide is at least 80 percent bromide. Preferredemulsions employed in the process can be generally characterized asbeing high-speed emulsions and in a preferred embodiment the process isused for processing (i.e., developing, fixing, washing and drying)high-speed negative films, reversal films, medical X-ray films, and thelike. Generally, these emulsions can be sensitized using any of thewell-known techniques in emulsion making, e.g., by digesting withnaturally active gelatin or various sulfur, selenium, telluriumcompounds and/or gold compounds. The emulsions can also be sensitizedwith salts of noble metals of Group VIII of the Periodic Table whichhave an atomic weight greater than 100.

The light-sensitive compositions containing the acrylic interpolymersdescribed herein can be coated on a wide variety of supports: inpracticing this invention. The emulsion compositions can be coated onone or both sides of the support which is preferably transparent and/orflexible. Typical continuous supporting sheets include, for example,cellulose nitride film, cellulose acetate film, polyvinyl acetal film,

polystyrene film, polyethylene terephthalate film and other polyesterfilm as well as glass, paper, metal, wood, and the like. Supports suchas paper can be coated with alpha-olefin polymers, particularly polymersof alpha-olefins containing two or more carbon atoms, as exemplified bypolyethylene, polypropylene, ethylenebutene, copolymers and the like.

In a preferred embodiment the light-sensitive compositions are coated onboth sides of the support to provide high image density with low X-rayexposures and fluorescent screens. The acrylic interpolymers can also beused in additional layers of the photographic element, such as in layersadjacent the silver halide emulsion and etc.

Hydrophilic colloid containing layers present in the elements employedin the practice of this invention can be hardened with any suitablehardener, including chrome alum, aldehyde hardeners such as formaldehydeand mucochloric acid, aziridine hardeners, hardeners which arederivatives of dioxane, oxypolysaccharides, such as oxy starch or oxyplant gums, and the like. The emulsions of this invention generally havea hardness value above about 195 F. said hardness value being themelting point temperature of the emulsion in water. In contrast,unhardened gelatin emulsions have a melting point of about to F. Thesilver halide layers or other layers in the element can also containadditional additives, particularly those known to be beneficial inphotographic elements including, for example, plasticizers, lubricatingmaterials such as long chain fatty acids, silicone resins, N-alkyl Bamino propionates, palmityl palmitate, and the like. The silver halidelayers described herein can also contain spectral-sensitizing dyes.Suitable spectral sensitizers of this type include the cyanines,merocyanines, complex (trinuclear) cyanines, complex (trinuclear)merocyanines, styryls and hemicyanines. The silver halide layers canalso be developed using incorporated developers such aspolyhydroxybenzenes, aminophenols, 3-pyrazolidones and thelike.

As indicated in U.S. Pat. No. 3,142,568, issued issued July 28, I964, itis sometimes advantageous to include a surface active agent orcompatible mixtures of such agents in the preparation of vinyl oraddition polymers and in coating photographic materials containing suchpolymers. Suitable wetting agents include the nonionic, ionic andamphoteric types as exemplified by the polyoxyalkylene derivatives,amphoteric amino acid dispersing agents, including sulfobetaines and thelike. Such wetting agents are disclosed in U.S. Pat. No. 2,600,831issued June 17, I952; U.S. Pat. No. 2,271,622, issued Feb. 3, i942; U.S.Pat. No. 2,271,623, issued Feb. 3, l942; U.S. Pat. No. 2,275,727, issuedMar. 10, 1942 and U.S. Pat. No. 2,787,604, issued Apr. 2, 1957; U.S.Pat. No. 2,816,920, issued Dec. 17, I957, U.S. Pat. No. 2,739,891,issued Mar. 27, 1956, and British Pat. No. 1,022,878.

The emulsion can also contain additional additives, particularly thoseknown to be beneficial in photographic emulsions including, for example,stabilizers or antifoggants, particularly noble metal compounds asdisclosed in U.S. Pat. No. 2,566,245; U.S. Pat. No. 2,566,263, and U.S.Pat. No. 2,597,856, the substituted triazaindolizines as disclosed inU.S. Pat. Nos. 2,444,605, and 2,444,607, speed increasing materials,absorbing dyes, and the like, Sensitizers which give particularly goodresults in the photographic compositions disclosed herein are thealkyleneoxide polymers which can be employed alone or in combinationwith other materials, such as quaternary ammonium salts, as disclosed inU.S. Pat. No. 2,886,437 or with mercury compounds andnitrogen-containing compounds as disclosed in U.S. Pat. No. 2,75 L299.

As already indicated certain classes of compounds can be used in thephotographic elements described herein to modify developmentcharacteristics and thereby provide a photographic element with severalimproved photographic properties. The development modifiers which can beemployed with the emulsions of this invention are nitroazoles andmercaptoazoles in which nitrogen is the .sole hetero atom andanthraquinone-2-sulfonic sulfonic acids and their alkali-metal salts.The preferred nitroazoles and mercaptoazoles have five memberedheterocyclic rings containing at least one nitrogen atom; very goodresults are obtained with nitroazoles such as the indazoles and themercaptoazoles such as the tetraazoles.

The preferred nitroazoles include the nitrobenzodiazoles such as theS-nitrobenzodiazoles, sometimes named as 6- nitrobenzodiazoles due tothe presence of two nitrogen atoms in the heterocyclic ring asexemplified by S-nitroindazole, 5- nitrobenzimidazole and the like. TheS-nitrobenzodiazoles are employed in concentrations of about 0.1 toabout 50 millimoles per mole of silver halide and preferably about 1 toabout millimoles. Compounds of this type are disclosed in U.S. Pat. No.2,214,445 issued Sept. 10, 1940.

The S-mercaptotetrazole compounds which can be employed in the practiceof this invention include those having the formula:

where R is an aliphatic or aromatic radical containing up to 30. carbonatoms and SX is a mercapto function. The mercapto function or group canbe in the free (-811) form or in the salt (-SX) form. X is a cation, forexample, hydrogen, an alkali metal such as sodium, potassium, ammoniumor an organic amine residue of such amines as triethyl amine, triethanolamine, morpholine and the like. in addition, many of the mercaptoheterocyclic nitrogen compounds can be in the tautomeric form, forexample, in the thione form, in which case the labile hydrogen atom inthe mercapto function becomes bonded to the nitrogen atom and the C-SXgroup becomes a thiocarbonyl groups. The term S-mercapto tetrazole, asemployed herein, is intended to cover compounds in which the mercaptofunction is in any of these forms. R can be hydrocarbon ornonhydrocarbon and includes alkyl or aryl radicals which can containatoms or groups other than carbon and hydrogen. Suitable atoms or groupswhich can be present in R together with hydrogen and carbon include, forexample, alkoxy, phenoxy, halogen, cyano, nitro, amino, substitutedamino, sulfo, sulfamyl, substituted sulfamyl, sulfonylphenyl,sulfonylalkyl, sulfonamidophenyl, sulfonamidoalkyl, carboxy,carboxylate, carboxyphenol, acetamidophenyl, carbamyl, carbamylphenyl,carbamylalkyl, carbonylalkyl carbonylphenyl and similar groups. Examplesof 5-mercapto tetrazoles which can be employed in the practice of thisinvention include l-phenyI-S-mercapto tetrazole, l-ethyl-S-mercaptotetrazole, l-anaphthyl mercapto tetrazole, l-cyclohexyl-S-mercaptotetrazole, l-(3-acetamidophenyl)-5-mercapto tetrazole, l-(3,5-dicarboxyphenyl)-5-mercapto tetrazole, and the like. The mercaptoazoles are employed in concentrations of generally about 0.1 to 50millimoles per mole of silver halide and preferably about 1 to about 15millimoles. Compounds of this type are disclosed in U.S. Pat. No.2,403,927 issued July 16, 1946; U.S. Pat. No. 2,271,229 issued Jan. 27,1942; and U.S. Pat. No. 3,266,897 issued Aug. 16, 1966.

The anthraquinone sulfonic acids or salts employed in the practice ofthis invention are derivatives of anthraquinone and contain a sulfonicacid function in the 2 position. The sulfonic acid function can be inthe free (SO;,l-l) form or in the salt (-SO M) form. M is a cation, forexample, hydrogen or an alkali metal such as sodium, potassium,ammonium, an organic amine residue of such amines as triethyl amine,triethanol amine, morpholine, and the like. Suitable anthraquinonesulfonic acids or salts which can be employed in the practice of thisinvention include, for example, anthraquinone-2-sulfonic acid,anthraquinone-2,6-disulfonic acid, anthraquinone-2,7- disulfonic acid,anthraquinone-l,2-disulfonic acid, and the like as well as salts,particularly alkali metal salts thereof. The anthraquinone derivativesare employed in concentrations of generally about 0.1 to 50 millimolesper mole of silver halide and preferably about l-15. Compounds of thistype are disclosed in U.S. Pat. No. 2,504,593 issued Apr. 18, 1950.

lnert particles can be incorporated into one or more layers of theelement, e.g., to control static discharge or to enhance developerpickup. The inert particles employed for this purposes are waterinsoluble, solid particles, and can have an average size within a broadrange. Preferred inert particles have a diameter in the range of about 5millimicrons to about 15 microns.

The inert particles employed in the practice of this invention includeany of the water insoluble particulate organic or inorganic compoundswhich can be used to provide the photographic element with the requiredsurface characteristics. Examples of suitable inert particles includestarch, barium sulfate, calcium carbonate, cellulose esters such ascellulose acetate propionate, cellulose others such as ethyl cellulose,synthetic resins such as polymeric esters of acrylic and methacrylicacid, as exemplified by poly methyl methacrylate, polyvinyl resins suchas polyvinyl acetate, polycarbonates, homoand copolymers of styrene,inorganic oxides such as zinc oxide, silica, glass, titanium dioxide,magnesium oxide and aluminum oxide, as well as hardened gelatin grains,calcium carbonate, barium carbonate and the like. Particularly usefulare silica particles having a particle size less than 50 my. asdescribed in U.S. Pat. No. 3,053,662 issued Sept. 11, 1962, and U.S.Pat. No. 2,892,797 issued June 30, 1959.

The discrete particles can be incorporated into one or more layers on anemulsion side surface of a support in a photographic element. The inertparticles can also be put into both the photographic silver halideemulsion layer and an adjacent layer such as a gelatin layer coated overthe emulsion layer.

The solid inert particles are incorporated into the photographic elementof this invention using any method which will achieve uniform dispersionof the particles in one or more layers of the element. For example, theinert particles can be dispersed directly in a photographic silverhalide coating solution or they can be dispersed in an aqueous solutionor dispersion of the silver halide binding agent, which solution ismixed with a photographic silver halide emulsion prior to coating thelatter to form a light sensitive layer. ln general, the solid inertparticles are present in the photographic element in concentrations inthe range of about 20 to about 150 preferably about 30 to about 100mg./ft. of support.

Upon proper selection of the proper processing solutions and processingconditions, the photographic elements of this invention can be processedand dried properly in an actual processing time of less than 2 minutesand preferably as short as 30 seconds (not including the time oftransport between the various processing solutions and a dryingchamber). A typical total processing time obtainable in the presentprocess is 60 to 120 seconds from the point of feeding the film into atransport apparatus to the emergency of the dried film. ln a typicalprocess for developing X-ray film the pH of the developer should bemaintained at from about 9.5 to 10.5 using, for example, caustic alkalior alkali metal carbonate. The pH is selected to insure that developmentproduces an X-ray image of the desired density and contrast at theselected time and temperature. The temperature of the developingsolutions should be maintained between about and 120 F. Under theseconditions, development is carried out until the required density andcontrast is obtained; a useful development time is 25 seconds in a60second actual processing cycle including drying time, in a rollertransport system such as shown in the drawing, or seconds total timewhen including the time of transport of the film between the tanks anddrying chamber.

The fixing solution employed in the process of our invention is aconventional fixing solution containing a silver halide solvent such asalkali metal or ammonium thiosulfate. When employing the shorter actualprocessing times of the order of 30 seconds, a higher concentration ofthe silver halide solvent is used and conversely, the temperature of thefixing solution should be maintained at from about 80 to 120 F. Arepresentative fixing time is 12 seconds in a 60-second actualprocessing time.

Following treatment of the film in the fixing solution, it is washedwith water at about 80 to 120 F. until substantially all of thesolubilized silver salt has been removed from the film. A representativewashing time is 20 seconds at 120 F. in a 60-second actual processingtime.

After washing the film, it is preferably squeegeed to remove excesswater and dried at about 120 to 200 F. by directing a stream of airagainst the emulsion surface. ln a 60-second actual processing cycle,when the emulsion contains about 450 mg. of gelatin per square foot,drying can be expected to be complete in 20 seconds or less using astream of air of approximately 50 percent relative humidity.

In the process described it should be understood that the shorterprocessing times are best obtained by selection of emulsions containingthe minimum amount of colloid binder vehicle, the selection of thehigher processing temperatures and developing at the higher Ph values aswell as fixing with the more concentrated acid fixing solutions.Emulsions containing the higher levels of gelatino colloid vehiclerequire drying for longer periods of time at higher temperatures.

The accompanying drawing shows in schematic form a representative rollertransport system in commercial use for the development of X-ray film andparticularly adapted to use in our invention.

Cut sheet X-ray film having a silver halide emulsion layer coated onboth sides of the support is advanced along the path shown betweenstaggered rollers through the development, fixing and washing tanks andthrough the drying section. An apparatus of this type is described inmore detail in US. Pat. No. 3,025,779. In this apparatus, an actualprocessing time of 30 to 90 seconds is adequate. Other types of rollertransport apparatus can be employed in the process of out invention. Forexample, apparatus can be used of the type wherein the film is advancedby means of a series of rollers, through several chambers whereprocessing solutions aresprayed onto the emulsion surface within thementioned temperature ranges and the film dried at elevatedtemperatures.

This invention can be further illustrated by the following examples ofpreferred embodiments thereof although it will be understood that theseexamples are included merely for purposes of illustration and are notintended to limit the scope of the invention unless otherwisespecifically indicated.

EXAMPLE 1 A coarse-grained silver bromoiodide photographic emulsion ofthe type used for screen X-ray materials containing 68 grams ofgelatin/Ag mole is coated on both sides of a polyester, polyethyleneterephthalate support at 473 mg. Ag/ft. and 298 mg. of gelatin/ft? oneach side. This sample is used as a control for comparison with thefollowing emulsion.

A similar emulsion is prepared which contains 68 grams of gelatin and 68grams of copoly (butyl acrylate-sodium acryloyloxypropanesuIfonate-Z-acetoacetoxyethyl methacrylate) (Tg Less than C.) per moleof Ag. This emulsion is coated as above at 473 mg. Ag and 596 mg.vehicle/ft. on

Feature Haze All gelatin vehicle 1- Poor Gel: polymer vehicle 4 SlightSimilar improved properties are obtained when a copoly(methylacrylate-sulfopropyl acrylate); copoly (methylacrylate-sulfopropylacrylate-2-acetoacetoxyethyl methacrylate) andcopoly (methylacrylate-3-acryloyloxy-1-methyl propanel-sulfonic acid Nasalt) which all have Tgs of less than 10 C. are used as the acrylicinterpolymer in the emulsion.

ln contradistinction a similar emulsion containing poly (N- vinyllactam) when processed under similar conditions has a high haze leveland relatively poor wet abrasion resistance.

EXAMPLE 2 An emulsion is prepared by the procedure of Example 1 whichcontains 68 grams of gelatin and 68 grams of copoly (ethylacrylate-acrylic acid-Z-acetoacetoxyethyl methacrylate) per mole of Ag.The emulsion is coated and tested as in Example l with the followingresults.

Feature Haze Wet Abrasion All gelatin vehicle (control I PoorGel:polymer vehicle 3+ Slight Example 3 Mixtures of latex typeinterpolymers and the more soluble-.

solution-type interpolymers can be used effectively in this invention.An emulsion similar to that of Example 1 is prepared containing 55 gramsof gelatin, 15 grams of a latex polymer of copoly (butyl acrylate-sodiumacryloyloxypropane sulfonate- Z-acetoacetoxyethyl methacrylate) (Tg=lessthan 10 C.) and 40 grams of a more soluble polymer of copoly (ethylacrylate-' acrylic acid-2-acetoacetoxyethyl methacrylate) (Tg=less than10 C.) made from 24 weight percent acrylic acid monomer. All vehiclesare added in the given portions per mole of silver in the emulsion.

The emulsion also contained 650 mg. of S-nitroindazole and 20 mg. of1-phenyl-5-mercaptotetrazole per mole of silver.

The emulsion is coated on both sides of a polyethylene terephthalatesupport at 473 mg. Ag and 596 mg. of colloid vehicle per ft. on eachside of the support. A control sample contains an all gelatin vehiclewith no development modifiers.

The samplesare exposed, developed and tested as in Example 1 with thefollowing results. 1

Feature Haze Wet Abrasion All gelatin vehicle l Poor Gel: polymervehicle 3+ Slight EXAMPLE 4 A coarse-grained silver bromoiodidephotographic emulsion of the type used for screen X-ray materials isprepared containing 68 g. of gelatin and 68 g. of copoly (butylacrylatesodium acryloyloxypropane sulfonate-2-acetoacetoxyethylmethacrylate). To one portion of the emulsion is added 0.6 grams/Ag moleof 5-nitroindazole. Comparative sample of the emulsions are coated onboth sides of a polyester (polyethylene terephthalate) support at 473mg. Ag/ft. and 576 mg. of vehicle/ft. on each side.

The dried coatings are exposed for l/50 of a second to a simulatedscreen exposure and processed in a unidirectional roller transportprocessor, i.e., a Kodak X-Omat Processor, for seconds total processingtime as follows:

Development 20 seconds at F. in a 1-phenyl-3- pyrazolidone-hydroquinonedeveloper Fixing 12 seconds at 105 F. in an ammonium thiosulfateaceticacid fixer Washing 8 seconds at 105 F.

Drying 20 seconds at 105 F.

The remaining time was used in transporting the film between the tanks,i.e., the developing and drying sections.

The comparative results are as follows:

Feature I y I og D." Control 1.45 0.21 3.34 Control S-Nitroindazole 2.550.05 3.70

Similar improved results are obtained when the emulsions contain 0.5g./mole of -chlorobenzotriazole, 0.1 and 0.5 g./mole of S-methyll,2,3-benzotriazole, 0.1 g./mole of 3-mercapto-benzothiazole, 1.0 and 2.5g./mole of 5-carbethoxy-3-(3-carbethoxypropyl)-4-methyl-4thiazoline-2-thione, S-mercapto-l,2,4-triazole and sodium anthraquinone sulfonate.

EXAMPLE 5 A coarse-grained silver bromoiodide photographic emulsion ofthe type used for screen X-ray materials is prepared containing 68 g. ofgelatin and 68 g. of copoly (ethyl acrylate acrylicacid-Z-acetoacetoxyethyl methacrylate).

To one portion of the emulsion is added 50 mg./Ag mole ofphenyl-S-mercapto tetrazole (PMT). The emulsion was coated, exposed, andprocessed as in Example 3 with the following results.

Feature 1 Fog D Control 0.89 0.33 1.65

Conlrol+ PMT 1.17 0.15 1.69

Similar results are obtained when phenyl-S-mercapto tetrazole is used incombination with the acrylic interpolymers: copoly (methylacrylate-sulfopropyl acrylate), copoly (methyl acrylate-sulfopropylacrylate-2-acetoacetoxyethyl methacrylate) and copoly (butylacrylate-acrylic acid- Z-cyanoacetoxyethyl methacrylate).

Not all compounds act as development modifiers in the emulsions of thisinvention. While some commonly used photographic additives do improvefog characteristics slightly, they have either no effect or an adverseeffect on the sensitometric characteristics of the emulsion.

A coarse grained silver bromoiodide photographic emulsion is preparedaccording to Example 1 containing 68 grams per mole of silver of copoly(butyl acrylate-sodium acryloyloxypropane sulfonate-2-acetoacetoxyethylmethacrylate).

The addenda listed in the following table were added to respectivesamples of the emulsion. Each sample is coated on both sides of apolyethylene terephthalate support at 473 mg. of Ag per ft. and 596 g.of vehicle per ft. on each side. The coatings are exposed and processedaccording to Example 4 with the following results.

Addenda (gJmole of Ag) 7 Fog Control 0.88 0.21 4-hydroxy-6-methyl-l,3.3a,

7-tetrazaidene (2) 0.86 0.21 Methyl D-arabonate (10) 0.80 0.21l.l0-bis(piperidino)-l .10

-dioxo 2.5,6,9-tetrathiadecane In a highly preferred embodiment theemulsions of this invention contain carboxy substitutedl-phenyl-Smercaptotetrazoles. The carboxy substitutedl-phenyl-S-mercaptotetrazoles control the background fog at a low levelin the emulsions of this invention without the desensitizationassociated with many antifoggants.

EXAMPLE 6 A coarse-grained silver bromoiodide photographic emulsion ofthe type used for screen X-ray materials containing 120 grams ofgelatin/Ag mole is coated on a polyester, polyethylene terephthalate,support at 484 mg. Ag/ft. and 538 mg. gelatin/ft This sample is used asa control for comparison with the following emulsion.

A similar emulsion is prepared which contains 55 grams of gelatin and 55grams of the alkyl acrylate copolymer, copoly (ethyl acrylate-acrylicacid-Z-acetoacetoxyethyl methacrylate) per mole of silver. To respectiveportions of this emulsion are added 50 mg. and 100 mg. of1-(3,5-dicarbosyphenyl)-5-mercaptotetrazole (A) per mole of silver and25 mg. of phenyl mercaptotetrazole (B) per mole of silver. Therespective samples were coated on a polyester support after thespecified hold period listed in the table below at 484 mg. of Ag/ft? and538 mg. of vehicle per ft The above coatings are given a simulatedscreen exposure and developed for 3 minutes in an Elon-hydroquinonedeveloper, fixed, washed and dried with the following results.

Addenda Hold Emulsion (mg/Ag Before Rel.

Vehicle mole) Coating Speed 1 Fog Gelatin None 100 1.63 0.06

Gelatin-polymer None 100 1.67 0.05 Gelatin-polymer 4 hour 67 1.32 0.18Gelatin-polymer A (50) 4 hour 91 1.98 0.10 Gelatin-polymer A (100) 4hour 95 1.68 0.04 Gelatin-polymer B (25) 4 hour 16 1.77 0.04

It is apparent that the carboxy substitutedl-phenyl-S-mercaptotetrazoles provide an increase in sensitivity of theemulsion while controlling the fog at low levels.

The invention has been described in considerable detail with referenceto preferred embodiments thereof, but it will be understood thatvariations and modifications can be effected within the spirit and scopeof the invention as described hereinabove and as defined in the appendedclaims.

We claim:

1. A high-speed silver halide photographic emulsion comprising (l)gelatin, (2) an interpolymer comprising units of an alkyl acrylate, saidinterpolymer comprising between about 10 percent and about 99 percent,by weight, of the binder vehicle for the said emulsion, being compatiblewith gelatin and having a Tg of less than about 20 C., and (3)nitroazole, mercaptoazole or anthraquinone-2-sulfonic acid developmentmodifier, said halide being at least mole percent bromide, and saidemulsion being chemically sensitized with a compound of sulfur,selenium, tellurium or gold or a salt of a Group VIII noble metal havingan atomic weight greater than 100.

2. An emulsion according to claim 1 wherein said development modifier isa mercaptotetrazole.

3. An emulsion according to claim 1 wherein said development modifier isa nitroindazole.

4. An emulsion according to claim 1 wherein said development modifier isa nitroazole or mercaptoazole having a 5 membered heterocyclic ringcontaining a nitrogen atom.

5. An emulsion according to claim 1 wherein said development modifier isa carboxy substituted l-phenyl-S-mercaptotetrazole.

6. An emulsion according to claim 1 wherein said development modifier isl-(3,5-dicarboxyphenyl)-5-mercaptotetrazole.

7. The emulsion of claim 1 wherein the interpolymer is copoly (butylacrylate-sodium acryloyloxypropane sulfonate- Z-acetoacetoxyethylmethacrylate 8. The emulsion of claim 1 wherein the interpolymer iscopoly (methyl acrylate-sulfopropyl acrylate).

9. The emulsion of claim 1 wherein the interpolymer is copoly (methylacrylate-sulfopropylacerylate-2-acetoacetoxyethyl methacrylate).

10. The emulsion of claim 1 wherein the interpolymer is copoly (methylacrylate-3-acryloyloxy-l-methyl propane-1- sulfonic acid, sodium salt).

11. The emulsion of claim 1 wherein the interpolymer is copoly (ethylacrylate-acrylic acid-2-acetoacetoxyethyl methacrylate).

12. The emulsion of claim 1 wherein the interpolymer is copoly (butylacrylate-acrylic acid-2-cyanoacetixtethyl methacrylate).

13. The emulsion of claim 1 wherein the interpolymer is copoly (butylacrylate-sodium acryloyloxypropane sulfonate- 2-acetoacetoxyethylmethacrylate) and the development modifier is 5-nitroindazole.

14. The emulsion of claim 1 wherein the interpolymer is a mixture ofcopoly (ethyl acrylate-acrylic acid-Z-acetoacetoxyethyl methacrylate)and copoly (butyl acrylate-sodium acryloyloxypropanesulfonate-2-acetoacetoxyethyl methacrylate), and the developmentmodifier is a mixture of 5-nitroindazole andl-phenyl-5-mercaptotetrazole.

ment modifier is l-phenyl-S-mercaptotetrazole.

20. The emulsion according to claim 1 wherein the development modifieris sodium anthraquinone sulfonate.

2l. The emulsion according to claim I wherein the development modifieris S-chlorobenzotriazole.

22. The emulsion according to claim 1 wherein the development modifieris S-methyl-1,2,3-benzotriazole.

23. The emulsion according to claim 1 wherein the development modifieris 3-mercaptobenzothiazole 24. The emulsion according to claim 1 whereinthe development modifier is 5-carbethoxy-3-(3-carbethoxypropyl)-4-methyl-4-thiazoline-2-thione.

25. The emulsion according to claim 1 wherein the development modifieris 3mercaptol ,2,4-triazole.

gz g UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTEON Patent No. 32 ,459 Dated March 7, 1972 Inventor) Robert C. Taber and Willima H.Russell It: is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 32, "U.S. Pat. No. should read --U.S. Serial No.---; line35, delete "aoetoaoetoxy-ethyl"; line 75, "nitride" should read---nitrate---. Column L line 75, delete the first "sulfonio". Column 5,line 13, "U.S. Pat. No, 2,21h,l l 5"' should read U.S. Patent 2,2lh,L1 L,6. Column 6, lines 5 and 6, "purposes" should read ---purpose---; line60, "emergency" should read --emergence---. Column 7, line 39, outshould read --our---. Column 8, line 5h, "sample" should read-samples---., Column 9, line 70, "1(3,5'-dioarbosyphenyl)-5-mereaptotetrazole should read -----l (3,5--dicarboxyphenyl)-5-mercaptotetrazole; Column 10, Claim 9,"sulfopropylaeerylate" should read ---sulfopropylacrylate---.

Signed and sealed this lst day of August 1972.

(SEAL) Attest:

ROBERT GDTTSCHALK Commissioner of Patents EDWARD M.FLETCHER,JR.Attesting Officer

2. An emulsion according to claim 1 wherein said development modifier isa mercaptotetrazole.
 3. An emulsion according to claim 1 wherein saiddevelopment modifier is a nitroindazole.
 4. An emulsion according toclaim 1 wherein said development modifier is a nitroazole ormercaptoazole having a 5 membered heterocyclic ring containing anitrogen atom.
 5. An emulsion according to claim 1 wherein saiddevelopment modifier is a carboxy substituted1-phenyl-5-mercaptotetrazole.
 6. An emulsion according to claim 1wherein said development modifier is1-(3,5-dicarboxyphenyl)-5-mercaptotetrazole.
 7. The emulsion of claim 1wherein the interpolymer is copoly (butyl acrylate-sodiumacryloyloxypropane sulfonate-2-acetoacetoxyethyl methacrylate).
 8. Theemulsion of claim 1 wherein the interpolymer is copoly (methylacrylate-sulfopropyl acrylate).
 9. The emulsion of claim 1 wherein theinterpolymer is copoly (methylacrylate-sulfopropylacerylate-2-acetoacetoxy-ethyl methacrylate). 10.The emulsion of claim 1 wherein the interpolymer is copoly (methylacrylate-3-acryloyloxy-1-methyl propane-1-sulfonic acid, sodium salt).11. The emulsion of claim 1 wherein the interpolymer is copoly (ethylacrylate-acrylic acid-2-acetoacetoxyethyl methacrylate).
 12. Theemulsion of claim 1 wherein the interpolymer is copoly (butylacrylate-acrylic acid-2-cyanoacetixtethyl methacrylate).
 13. Theemulsion of claim 1 wherein the interpolymer is copoly (butylacrylate-sodium acryloyloxypropane sulfonate-2-acetoacetoxyethylmethacrylate) and the development modifier is 5-nitroindazole.
 14. Theemulsion of claim 1 wherein the interpolymer is a mixture of copoly(ethyl acrylate-acrylic acid-2-acetoacetoxyethyl methacrylate) andcopoly (butyl acrylate-sodium acryloyloxypropanesulfonate-2-acetoacetoxyethyl methacrylate), and the developmentmodifier is a mixture of 5-nitroindazole and1-phenyl-5-mercaptotetrazole.
 15. The emulsion of claim 1 wherein theinterpolymer is copoly (ethyl acrylate-acrylic acid-2-acetoacetoxyethylmethacrylate) and the development modifier is1-phenyl-5-mercapto-tetrazole.
 16. The emulsion of claim 1 wherein theinterpolymer is copoly (ethyl acrylate-acrylic acid-2-acetoacetoxyethylmethylacrylate) and the development modifier is1-(3,5-dicarboxyphenyl)-5-mercaptotetrazole.
 17. The emulsion of claim 1wherein the interpolymer is copoly (butyl acrylate-sodiumacryloyloxypropane sulfonate-2-acetoacetoxyethyl methacrylate) and thedevelopment modifier is sodium anthraquinone sulfonate.
 18. The emulsionaccording to claim 1 wherein the development modifier is 5nitroindazole.19. The emulsion according to claim 1 wherein the development modifieris 1-phenyl-5-mercaptotetrazole.
 20. The emulsion according to claim 1wherein the development modifier is sodium anthraquinone sulfonate. 21.The emulsion according to claim 1 wherein the development modifier is5-chlorobenzotriazole.
 22. The emulsion according to claim 1 wherein thedevelopment modifier is 5-methyl-1,2,3-benzotriazole.
 23. The emulsionaccording to claim 1 wherein the development modifier is3-mercaptobenzothiazole.
 24. The emulsion according to claim 1 whereinthe development modifier is5-carbethoxy-3-(3-carbethoxypropyl)-4-methyl-4-thiazoline-2-thione. 25.The emulsion according to claim 1 wherein the development modifier is3-mercapto-1,2,4-triazole.